The present invention relates to industrial vehicles such as forklifts, and more specifically, to a lifting mechanism controller and an industrial vehicle having the lifting mechanism controller.
Japanese Unexamined Patent Publication Nos. 7-2496 and 7-61792 describe a controller that controls the fork and the mast of a forklift, independent of manipulation by the driver. The controller stores a map for controlling movements of the fork and mast. The Publications describe a position sensor for detecting the fork position and the mast angle and a state sensor for detecting the operating state of the vehicle. The controller sets a target value corresponding to a target fork height (or mast angle) based on a detection value of the state sensor and the map. When the position sensor detects a value corresponding to the target value, the controller stops the movement of the fork (or mast).
The installed position of the fork, mast and the position sensor with respect to a vehicle body varies in each vehicle. As a result, for a given value detected by the position sensor, the actual position of the fork and mast varies from one vehicle to another. In the prior art, the values corresponding to the target position of the fork and mast are stored in a map in advance. However, the stored data is shared by various vehicles and this lowers the precision of controlling the target position of the fork and mast.
This may cause problems when high precision is required in limiting the movement of the fork and mast. Therefore, there is a need for a controller that precisely controls the position of the fork and mast in consideration of the various installed positions of the fork, mast and sensor.